ΔE 11.3, fair: the same colour family, but not a straight swap. Dark Sea Grey is a little darker, more muted than Field Gray.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Dark Sea Grey is a little darker, more muted than Field Gray.
The same difference applies the other way round: Field Gray is a little lighter, more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Field Gray on the colour wheel See Dark Sea Grey on the colour wheel
All matches: Field Gray equivalents · Dark Sea Grey equivalents